1. Field of the Invention
The invention relates to a power conversion technique, and more particularly, to a flyback-based power conversion apparatus.
2. Description of Related Art
The primary purpose of applying a power conversion apparatus is to convert an unstable and high alternating current input voltage supplied by the power company to a stable and low direct current (DC) output voltage suitable for various electronic devices. Therefore, the power conversion apparatus is widely used in computers, office automatic facilities, industrial control equipments, communication apparatuses and so on.
Pulse width modulation (PWM) control chip is applied in most of the control structures of recent power conversion apparatuses. To protect the power conversion apparatus from being damaged because of over voltage (OV) and over current (OC), the PWM control chip usually has a plurality of isolated detection pins for respectively executing detection and protection mechanisms, such as over current protection (OCP), valley voltage detection and over voltage protection (OVP). In other words, each of the detection pins of the PWM control chip is only corresponding to one type of function detections, and thus the overall production cost of the PWM control chip is difficult to be lowered.